With the continuing advances in microprocessors and other computer hardware it is increasingly common to design data processing systems in the form of multitasking systems comprising several, quasi-independent processes that operate simultaneously or as if simultaneously via time division. Interaction among such processes is frequently accomplished by passing `messages` between the processes, and facilities for messaging are often included in operating system software. Examples of such operating systems are the "psos" operating system published by Software Components Group, Inc., Santa Clara, Calif., and the "RMX" operating system published by Intel Corporation, Santa Clara Calif.
Thus an application program comprising several functions may be written to run under an operating system that provides messaging between the-processes. However, it frequently becomes necessary to run the application program, or some of the processes, under an operating system other than the operating system for which the application program was first written. For example, sometimes a desire to change the hardware for the data processing system requires that a new operating system be used. In these cases, the application program must be "ported" to the new operating system, and adapted to use the new operating systems messaging facilities. This may require considerable modifications to the application program, with attendant costs, delays and so forth.
It is therefore to be desired that messaging between the processes be carried out in such a way that the application program may be readily adapted to operate with different operating systems. It is also desirable to design a messaging method that facilitates program debugging.